1. Field of the Invention
The present invention relates to an electrical connector and, more particularly, to a longitudinally actuated zero force electrical connector in which the longitudinal movement of an actuator plate forces opposing contact holders and contacts engaging such holders apart when the high point of a cam surface which forms a part of the actuator plate engages a corresponding cam follower which forms a part of each contact holder. Similarly, such longitudinal movement allows the opposing contact holders and contacts to move toward each other when the low point of the cam surface engages the cam follower.
2. Description of Prior Art
Prior art attempts have been made to reduce or eliminate the contact between the terminals of a printed circuit board and opposing electrical contacts when the board is inserted into a connector of the type used to interconnect the connector's resilient contact members with the board terminals. For example, in U.S. Pat. No. 3,710,303 a connector is provided having means to shift the contact elements out of the insertion path of the circuit board as a result of the engagement, during insertion, between the circuit board and cam projections which form part of the connector. In the structure described, such cam projections extend further inward from the channel walls of the housing of the connector than do the contacts. When a circuit board is inserted into the channel the board engages the projections and displaces the projections away from the longitudinal axis of the channel. Due to the interrelationship between the projections and the contacts, the displacement of the projections causes a corresponding displacement of the contacts such that the contacts are displaced out of the path of the board. When the board is completely inserted into the connector, the cam projections enter recesses in the board. Such movement of the projections into the recesses causes corresponding movement of the contacts into engagement with the surface of the board, thereby electrically connecting the contacts to the board terminals. Although such devices reduce the contact between the board terminals and the connector contacts, the physical engagement between the board and the cam projections may require that more force than is desired be exerted to insert or remove the board in some applications.
In U.S. Pat. No. 3,478,301 an electrical connector is provided in which only after partial insertion of the printed circuit board is engagement of the connector contacts with the board contact terminals effected. In this structure, an elongated hollow body which forms the connector receptacle includes therein cam means which are actuated automatically by the insertion of a printed circuit board to displace resilient contacts into engagement with corresponding circuit board terminals. In operation, even though the circuit board has been partially inserted into the connector receptacle, there is no engagement with the contacts. After partial insertion, continued insertion causes the printed circuit board to actuate the cam means such that the board engages levers or lugs thereby pivoting cam lobes which bring resilient contact fingers into engagement with circuit board terminals. By moving the circuit board further into the receptacle toward the final position of the board, the contacts effect a wiping action against the terminals until the contacts are locked in resilient engagement with corresponding terminals. Although such devices eliminate the contact between the board terminals and the connector contacts as the board is being initially inserted into the connector, the physical engagement between the board terminals and connector contacts as the board is moved further into the connector may require that more force than is desired be exerted to complete the insertion and lock the contacts in engagement with the terminals. Similarly, such engagement may require relatively more force than is desired to remove the board from the connector and may cause undesirable wear of the contacts and board terminals.
Efforts have been made to provide a zero force connector in which the engagement of the connector contacts with the printed circuit board terminals is not effected until after the board has been inserted in the connector to the extent desired. For example, in U.S. Pat. No. 3,475,717 a zero force connector is provided having actuator plates which are slidably disposed within the connector housing to engage and disengage the resilient contacts per se. When the actuator plate engages such contacts, it flexes the contacts into engagement with the printed circuit board terminals. When the actuator plate is disengaged from such contacts, the inherent resiliency of the contacts causes the contacts to be biased away from the printed circuit board terminals. Although such a device may reduce the force required to insert a terminal board into a connector, inherent in the operation of such connectors is undesirable engagement between the actuator plates and the connector contacts.
Finally, in U.S. Pat. No. 3,526,869, a cam actuated connector is provided which includes an actuating cam, the rotation of which causes a bearing surface to engage an actuating surface to thereby move an actuating housing in a longitudinal direction. The housing comprises ramp sections which slide, as a result of such longitudinal movement, relative to ramp portions of actuator spacers to cause the actuator spacers to move inwardly or outwardly relative to the longitudinal axis of the housing. Such movement of the spacers causes corresponding movement of the contacts which engage the terminals of the printed circuit board. Although such a device may reduce the force required to insert a terminal board into a connector, the operation of this device requires a mechanism whereby rotational motion must be translated into longitudinal motion.
In addition to all of the foregoing, some prior art connectors have not proved to be totally satisfactory in that they have not been constructed to hold up under continuous use. Other prior art connectors have included complex structures which require that the connector be larger than desired.
It is therefore one of the objects of the present invention to provide a connector which will permit substantial reduction, or elimination, of the engagement between the terminals of a printed circuit board and opposing electrical contacts of the connector except for such time as the board is inserted into the connector to the extent desired.
Another object of the present invention is to provide a connector the use of which requires a minimum amount of force to insert a printed circuit board therein, or remove it therefrom.
A further object of the present invention is to provide a connector wherein the physical contact between the connector contacts and board terminals is substantially reduced except for such time as the board is inserted into the connector to the extent desired.
Yet a further object of the present invention is to provide a connector wherein any undesirable wear of the board terminals or connector contacts is substantially reduced.
Yet another object of the present invention is to provide a connector which does not require the translation of rotational motion into longitudinal motion during operation.
A further object of the present invention is to provide a connector which may be readily miniaturized.
Yet a further object of the present invention is to provide a connector which is simple in construction and durable even when subjected to continued use.
Another object of the present invention is to provide a cam surface which varies from its high point to low point in such a manner that the associated contacts are caused to move, relative to the longitudinal axis of the connector, more slowly as the contacts are deflected away from such longitudinal axis and the load in the resilient contacts is thereby increased.
A further object of the present invention is to provide means for guiding the actuator plate to facilitate longitudinal movement thereof.
Yet a further object of the present invention is to provide means to limit the stroke of the actuator plate along the longitudinal axis.
Yet another object of the present invention is to provide a connector into which a printed circuit board may be inserted either vertically (from above) or horizontally (from the side).
These and other objects will become apparent from the detailed discussion which follows and from the accompanying drawings.